Testing for Radon in Water

My husband and I recently purchased a home, 26 years old, and are in the process of fixing it up. It has been suggested that we test for radon in the well and will do this. My question is who is the most reliable source to take the water sample to? Are there certifications that we should be looking for? I am not interested in a water purification system. Thank you for your suggestions.

You take a properly collected water sample to a lab, or have a radon treatment dealer take it.

If you find too much radon in the water, you will end up wanting treatment equipment but it won't be a "purification system". There is no such thing as "pure" water. The best man can do is 18 megohm DI water.